Exploring the Effects of Heat Treatment on Sapphires All Entries
Sapphires can withstand incredible temperatures without being damaged, much higher temperatures in fact than many of the mineral inclusions that commonly occur in this stone. To take advantage of a sapphire’s heat tolerance, the process of heating was developed many centuries ago. During this process a sapphire is heated to the point where the inclusions start to melt. The temperature is maintained at this level for a couple of hours until the maximum amount of inclusions have dissolved and optimal clarity has been reached.
A sapphire’s color is determined by the interaction of minerals within the stone. An added benefit of heat treatment is that it causes the minerals to diffuse into the sapphire and in turn greatly enhances the gem's color. For example, in the case of a blue sapphire the color can be heavily enriched by the interaction of titanium and trace amounts of iron. On the other hand, depending on the amount of iron that is present in the stone, heat treatment can cause a sapphire that is greenish-yellow in color to turn deep yellow. Pink sapphires are not to be forgotten, heat treatment can produce a significant improvement in color by reducing tones of blue.
Heat treatment is widely recognised within the jewelry industry and can significantly improve two of the four characteristics that are used to grade sapphires, namely color and clarity. However, it is important to bear in mind that preference is given to non-treated sapphires that are organically clear and rich in color. High-end customers are willing to pay a hefty premium for the exclusivity of such stones. Because of this Ralph Mueller & Associates adheres to the code of ethics that require a seller to disclose any treatment that a stone has undergone. It is not to say that a treated sapphire is not valuable, if the heating process produces a highly desirable color, a treated sapphire can be of higher or equal value to an non-treated sapphire in a less desirable color.
Customers who value the exclusivity of an untreated sapphire will do well to look for gems sourced from Kashmir, Maynmar (previously known as Burma) and Ceylon. These three regions produce the world's most sought after sapphires, known for their exceptional natural blue tones and clarity. Unfortunately the fame of these regions have resulted in a de facto premium being charged for their products, and sapphires are often priced according to the brand rather than their individual quality and scarcity. When buying sapphires from these regions make sure the price is justified, if not, shop around, Thailand is another big player in the industry and produces magnificent sapphires with almost equal physical attributes to Burmese sapphires, at a much more affordable price point.
If you are already satisfied with the color and clarity of your sapphire it is recommended that you do not pursue heat treatment because the final color can not be guaranteed. Instead, consider faceting, a process of grinding and polishing, to maximize your sapphire’s brilliance and fire.
Visit our store in Phoenix to find out which is the right sapphire for you!